Color temperature is a kind of visible light that has important applications in lighting. The color temperature of a light source is the temperature of an ideal black-body radiator that radiates light of comparable hue to that of the light source. Color Temperature is a measurement in Degrees Kelvin that indicates the hue of a specific type of light source, the symbol of unit is K.

Different color temperature light of source also offer different light color, it will bring you a different feeling:

Higher color temperatures (5000K or more) are "cold", color is green to blue.